CONGESTION CONTROL IN GSM NETWORK

1.0 Introduction

The advents of wireless technology have had great impact on globalization of the Nigeria economy since its inception in 2001. But the tremendous growth in subscription have brought some challenges to the operators on how to tackle the occurring congestion in the mobile wireless communication posed in their services and have caused a lot of inconveniences to the subscribers. Since its goal is to provide good quality services to the end users (subscribers) with respect to speech, effective roaming globally and lesser tariffs. GSM has become more advanced and handles more subscribers than the analog systems(6). From the finding of our research, we have well over 9 million users of GSM contending for access almost at the same time in Nigeria, making the country one of the fastest growing GSM markets in Africa and the world at large(9). It is also has that the Nigeria telecommunication market is looking forward to achieve a tele density of 100% by the year 2020 which is driven by the massive telephone and mobile communication improvements thereby requesting for a great increase in the information and communication technology (ICT).

Nigeria, with the population density of over 170 million people are being serviced by five major Global System for Mobile (GSM) Telecommunication operators which are MTN, AIRTEL, GLOMOBILE, ETISALAT and MTEL. But among the various operators MTN has the greatest patronage with over 57.2 million subscribers although the competition is getting tighter as the day goes by as operates have to compete for the same potential subscribers.(1,9). Over the years after the start of the GSM era in Nigeria, the focus is now gradually shifting from providing coverage to providing quality service; and the euphoria of owning a phone set is gradually giving way to complaints of dropped calls and congestion among subscribers.

Hence, congestion simply means a state of being overcrowded, overloaded or blocked that is too full of traffic. This occurs when too many subscribers are contending or seeking for the use of the resources at almost at the same time which eventually will result to poor throughput, slow speed and poor network among the mobile wireless communication. Congestion is when too many packets are present in or a part at the subnet which results into the degradation of performance; that is when too many traffic is offered. This occurs when the incoming packets from the source node are too much for the router to handle which makes of streams of packet arriving on three or four input lines where all of them will share the same output line(6). When this happens, a queue will build up, causing congestion and finally if there is insufficient memory to hold the stream of packets, it will eventually results in the lost of some packets in the course of transmission. It can also be experience in a network when so many subscribers are contending for access simultaneously making the input traffic rate to exceed the capacity of the output line; when routers have an infinite amount of memory, congestion gets worse(9). However, congestion control is the controlling of traffic entry into a telecommunications network, in order to avoid congestive collapse. A system is said to be congested if it is being offered more traffic than its rated capacity due to too many active subscribers. System maintenance and repair actions can lead to system congestion but whatever be the cause of the overload, it will manifest as depletion of resources that are critical to the operation of the system. Also, Congestion control is differ from flow control in that a congestion is a global issue involving the behavior of all the hosts, routers, the store-and-forward processing within the routers while a flow control relates to the point-to-point traffic between a given sender and a given receiver.

Traffic is the use of given resources such as radio channels that is when a user makes a phone call, the channel is seized for communication resulting into generating traffic. Hence, traffic can be said to be proportional to the Average Call duration (6).

Network congestion can result when there is a rise in the transmission of a data thereby leading to a decrease in throughput. Also, it can occur as a result of sending more data than the network elements can accommodate thus causing the buffers on the network elements to be filled and possibly having an overflow(12). While traffic congestion is a condition on the GSM networks which occurs as the use increases and characterized by slower speeds, long trip times and queuing. This is experienced along several channels within the network architecture and occurs when the common, dedicated, traffic and pulse code modulation (PCM) channels are not available for the assignment for the incoming or outgoing service request. In summary, when backbone links fails, it shows to the available links have been over utilized (12). GSM is a cellular network, also known as mobile phones connected for cells searching in the immediate vicinity and operating in four different frequencies. There are five different cell sizes in a network namely macro, micro, Pico, femto and umbrella cells with their coverage area varying according to the implementation environment. Macro cells are regarded as cells where the base station antenna is installed on a mast or a building above average roof top level while micro cells are cells whose antenna height is under average roof top level and are typically used in urban centers (12). Hence, aimed to attempt to minimize and manage the effects of congestion on mobile wireless communication (GSM) by seeking to study critically the review and analyze the overview of the GSM network architecture, its mode of operations and the causes of traffic congestion which will provide an optimum preventive and control measure that will reduce the rate of congestion also improve the throughput of calls made. This will enhance the quality of service provided to the subscribers.

1.1 Background Of The Study

The current trend on the telephone technology is the cellular telephone usually referred to as the cell phone. A cellular telephone is designed to afford user a maximum degree of freedom of movement.

Consequently, there is a rapid increase in the cellular telephone density. Other factors are as well responsible for this growth and include reduction in service cost as well as the ever increasing range of services available through the cell phone. The cellular system began in the United States of America with the release of the Advanced

Mobile Phone Service (AMPS) system in year 1983 (Lee, 2006). Asia, Latin America and Oceanic countries adopted the AMPs standard creating the largest potential market in the world for cellular (Mehrotra, 1997).

GSM communication revolution in Nigeria started in August 2001 and this brought a great change in the face of Information and Communication Technology (ICT) (Adegoke et al., 2000).

In the early 1980s, most mobile telephone system was based on electronics technology. Some of the challenges facing analog systems are their inability to accommodate the growing bandwidth needs in a cost efficient manner because analog transceiver cannot handle more than one call at a point in time. Also several facilities as well as services are not possible in the analog system,. On the contrary, digital technology was welcomed. The advantages of digital system over analog system include ease of signaling lower level of interference, integration of transmission and switching as well as increased ability to meet capacity demands. Therefore the limitation of analog system become clearer as the number of subscribers increased. This gave way to the digital system. The GSM is more advanced than the analog system and uses digital data which accommodates more subscribers. This technology increased the number of subscriber beyond expectations.

The GSM mobile telephone offers high quality voice communications and low bandwidth, data connection for fax, short message services (SMS) as well as full dialup connection to the internet for e-mail and web browsing. The resultant effect is felt on emergence of mobile computers, the intelligent handset, the personal digital assistants (PDA) computer or intelligent handset. The need for mobile computing came as a result of the need to access information anywhere and anytime. The drawback of this system is its inefficient use of the radio resources.

The increasing need of mobile telephone and ancillary devices for data communication has driven the need for a fast, reliable and available infrastructure. Mobile communications are now showcases a wide range of services ranging from e-payment, e-government, e-health, etc. Mobile terminals are now becoming computer embedded system with stringent real time requirement for signaling and voice processing (Sconres,1997) it thus becomes imperative that numerous technical challenges bemoans its engineering and applications.

1.2 Aim And Objective Of The Study

Basically the aim of this project work is to design a congestion control system model for Etisalat Communication network. Other objective of this research work are:

1. To evaluate the core research to congestion within the network coverage
2. Highlight all the possible means for congestion control to the network — Etisalat Nigeria
3. Implement a hybrid system that will manage congestion control within the Etisalat communication network.
4. To analyze the effect of Etisalat network congestion to the growth of the communication network.

1.3 Research Questions

The research questions will be tailored towards the purpose of the study such that if they are answered, one will clearly realize why congestion control within the GSM network is necessary in the management of Etisalat network and its growth.

The questions are the following:

1. What are the current issues coursing congestion within the network communication coverage?
2. How effective is the model architecture on the present congestion control system?
3. Do you have an Etisalat SIM for communication?
4. If you do, how offend you use or prefer to use the network over the other network available?
5. Why do you use or not use the network often?

1.4 Research Hypothesis

This is the tool with which to test the reliability of the subject matter comparing the two variables — congestion control (independent variable) and Congestion (dependent variable). The hypotheses are:

H0- There is a significant relationship between network congestion and the growth management of Etisalat network

H1- There is no significant relationship between network congestion and the growth management of Etisalat network

1.5 Significance Of The Study

This study will help us to know the status of Etisalat GSM network congestion control in Nigeria with a view to knowing areas to be addressed for better performance. This research work will aid telecommunication companies (precisely Etisalat) in Nigeria to achieve a high performance level and optimal profit. This research work is also significant in other ways like:

1. Use Inter-switch to put calls through to the right designation without delay, distortions or diversion.
2. Determine the calling network and receiving network and use this information for the purpose of interconnectivity tariffs.
3. Maintain a database of all registered GSM lines for all GSM communication companies.

1.6 Scope And Limitation Of The Study

This research covers network connectivity and traffic control of Etisalat network in Nigeria. The system covers all forms of congestion within the network in forms of voice calls, data connection, SMS, Push SMS and Video calls across the network. Both call identification, recording and network interconnectivity.

Some of the constraints encountered during this project design include the following:

1. Financial Constraints: The design was achieved but not without some financial involvements. One had to pay for the computer time. Also the typing and planning of the work has its own financial involvements. However, to solve the problems I solicited fund from guardians and relations.
2. High programming Technique: The programming aspect of this project posed a lot of problematic bugs that took me some days to solve. Problems such as the ADO, DAO and Jet Engine related run time errors. For instance, the Ms Access office 2000 edition does not work with VB-6. Jet Engine unless converted to lower version of Ms ACCESS of office 1997 edition (i.e. version 2.0). Also other technical problem, which requires semantic and syntactic approaches where encountered as well. In seeking for the solution to these problems, I acquired more knowledge from well —versed textbooks and programmes.
3. The epileptic nature of power supply cannot be overlooked.

1.7 Definition Of Terms

Inter-switch:

Inter-Switch Link (ISL) is a trunking method developed by Cisco to use for Ethernet and Token Ring trunk connections.

Congestion:

It is the overcrowding of route, leading to slow and inefficient flow. In computing, it is a situation in which the amount of information to be transferred is greater than the amount that the data communication path can carry.

Air interface:

In a mobile phone network, the radio transmission path between the base station and the mobile terminal.

Asymmetric Transmission:

Data transmissions where the traffic from the network to the subscriber is at a higher rate than the traffic from the subscriber to the network.

SIM:

Subscriber Identity Module; A smart card containing the telephone number of the subscriber, encoded network identification details, the PIN and other user data such as the phone book. A user's SIM card can be moved from phone to phone as it contains all the key information required to activate the phone.

Telecommunication:

Are devices and systems that transmit electronic or optical signals across long distances. Telecommunication enables people around the world to contact one another to access information instantly, and to communicate from remote areas.

Computer Network:

It is a system used to connect two or more computers using a communication link.

1.8 Methodology

SSADM method was used also with the Image culture of everyday activities with use of DDCM monitoring and recording system from major books. Analytical method was used in this project also, it is recommended as the best control measure for GSM congestion. This research work has made it possible for some of the key performance indicators to reach a bench mark as recommended by the International Telecommunication Union.